BART's labor stoppage is polluting the air, wasting commuters' time and, at least by one estimate, costing the overall Bay Area economy $73 million per day.

The most public sticking points that led to the strike have been raises and pension contributions, a dispute that is separated by $17.53 million a year.

After comparing both labor and management's most recent publicly available offers, the dispute over wage increases and retirement plans boils down to a difference of $7 million and $10 million a year, respectively.

That's less than 5 percent of BART's total $403 million budget for wages and benefits.

BART's unions — Service Employees International Union Local 1021 and Amalgamated Transit Union Local 1555 — said Sunday that they are asking for 15 percent in raises over the next three years, or 5 percent a year, coupled with 0.5 percent employee contributions to pensions. Wages have been frozen since 2009, and workers do not pay into their pension plans.

BART, by contrast, is offering an 8 percent raise over four years, at 2 percent a year, or a total of $18.72 million.

That means the two parties are $28.08 million apart on raises, or about $7 million a year.

The biggest difference may be on pensions. BART's latest publicly known offer was to have employees contribute 5 percent of their checks to pensions; unions countered with a 0.5 percent contribution.

Based upon current earnings, that's $11.7 million in contributions toward $59.3 million in total pension costs versus $1.17 million.

Add it all up and it's a question of $17.53 million a year. That and a fight over working conditions, such as safety for workers and passengers, are keeping BART on strike.

BART management says labor savings are needed to cover the substantial costs of upgrades to its 41-year-old system.

The heart of the matter

A labor dispute is keeping BART trains idle this week. The argument boils down to $17.53 million per year, based on both sides' proposals and the transit agency's current budget.

$402 million: Total cost for wages and benefits for BART's 3,252 employees

$234 million: Total cost for wages

$168 million: Total cost for benefits

Benefits:

$59.3 million: Total cost of BART's pension plan

$10.4 million: Other pension benefits (BART's limited 401[a] plan)

$56.2 million: Medical insurance for current employees

$30 million: Medical insurance for retirees (1,797 retirees)

$12.4 million: Workers' compensation

WAGE INCREASE

Union proposal:

$35.1 million: 15 percent pay increase (5 percent annually over three years), $11.7 million per year

BART proposal:

$18.72 million: 8 percent pay increase (2 percent annually over four years), $4.68 million per year

$7.02 million: Wage increase difference between proposals

PENSION CHANGES

Pensions cost BART $59.3 million per year, and employees do not pay toward them.